Question

the ph scale for acidity is defined by ph = - log₁₀h⁺ where h⁺ is the concentration of hydrogen ions measured in moles per liter (m). (a) the ph of pure water is 7.0. calculate the concentration of hydrogen ions in moles per liter (m). h⁺ = m (b) the ph of lemon juice is 2.0. calculate the concentration of hydrogen ions in moles per liter (m). h⁺ = m

Explanation:

Part (A)

Step1: Start with the pH formula

We know that $\text{pH} = -\log_{10}[\text{H}^+]$. Given that the pH of pure water is 7.0, we substitute this value into the formula: $7.0 = -\log_{10}[\text{H}^+]$.

Step2: Solve for $[\text{H}^+]$

Multiply both sides by -1 to get: $-7.0 = \log_{10}[\text{H}^+]$. By the definition of a logarithm, if $\log_{b}a = c$, then $a = b^c$. So, $[\text{H}^+] = 10^{-7.0}$.

Step1: Use the pH formula

The formula is $\text{pH} = -\log_{10}[\text{H}^+]$. For lemon juice, pH = 2.0. Substitute this into the formula: $2.0 = -\log_{10}[\text{H}^+]$.

Step2: Solve for $[\text{H}^+]$

Multiply both sides by -1: $-2.0 = \log_{10}[\text{H}^+]$. Using the logarithm definition, $[\text{H}^+] = 10^{-2.0}$.

Answer:

$10^{-7}$ (or 0.0000001)

Part (B)